package club.hicode.daydayup.nio;

import org.junit.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;

/**
 * NIO 的学习测试
 *
 * @author Liu Chunfu
 * @date 2018-04-19 下午5:44
 **/
public class NioTest1 {

    //客户端
    @Test
    public void client() throws IOException {
        //1、获取通道
        SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8888));
        //2、切换非阻塞模式
        socketChannel.configureBlocking(false);

        //3、分配指定大小的缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);

        //4、发送数据服务器
        buf.put(new Date().toString().getBytes());
        buf.flip();
        socketChannel.write(buf);
        buf.clear();

        //5、关闭通道
        socketChannel.close();
    }

    //服务端
    @Test
    public void server() throws IOException {
        //1、获取通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        //2、切换非阻塞模式
        serverSocketChannel.configureBlocking(false);
        //3、绑定连接
        serverSocketChannel.bind(new InetSocketAddress(8888));

        //4、获取选择器
        Selector selector = Selector.open();

        //5、将通道注册到选择器上(第二个选项参数叫做选择键，用于告诉选择器需要监控这个通道的什么状态或者说什么事件（读、写、连接、接受）)
        //选择键是整型值，如果需要监控该通道的多个状态或事件，可以将多个选择键用位运算符“或”“|”来连接
        //这里服务端首先要监听客户端的接受状态
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        //6、轮询式地获取选择器上已经“准备就绪”的事件
        while (selector.select() > 0) {

            //7、获取当前选择中所有注册的“选择键（已就绪的监听事件）”
            Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();


            while (iterator.hasNext()) {
                //8、获取准备“就绪”的是事件
                SelectionKey sk = iterator.next();

                //9、判断是什么事件准备就绪
                if (sk.isAcceptable()) {
                    //10、若接受就绪，获取客户端连接
                    SocketChannel socketChannel = serverSocketChannel.accept();

                    //11、客户端连接socketChannel也需要切换非阻塞模式
                    socketChannel.configureBlocking(false);

                    //12、将该通道注册到选择器上，监控客户端socketChannel的读就绪事件
                    socketChannel.register(selector, SelectionKey.OP_READ);
                } else if (sk.isReadable()) {
                    //13、获取当前选择器上“读就绪”状态的通道
                    SocketChannel socketChannel = (SocketChannel) sk.channel();

                    //14、读取数据
                    ByteBuffer buf = ByteBuffer.allocate(1024);

                    int len = 0;
                    while ((len = socketChannel.read(buf)) > 0) {
                        buf.flip();
                        System.out.println(new String(buf.array(), 0, len));
                        buf.clear();
                    }
                }
                //15、取消选择键SelectionKey
                iterator.remove();
            }
        }
    }
}
